Abrasive bodies and methods of making same



July 3 1951 F. A. HEssl-:L ET AL 2,559,122

ABRASIVE BODIES AND METHODS OF' MAKING SAME Filed Oct. 19, 1944 PatentedJuly 3, 1951 UNIT-Eo STATES PATENT OFFICE ABR'ASIVE BODIES AND METHODS OMAKING SAME Frederick A. Hessel, Upper Montclair, and John AB. Rust,AMontclair, N. J., assignors, by direct and vrnes'ne assignments, ofone-half to Montclair Research Corporation, a corporation of New Jersey,and one-half to Ellis-Foster Company, a corporation of New J crseyapposition october 19, 1944, semi No. 559,446

characteristics oi" many of these prior art bind-' ers or bonding-agentsare unsatisfactory under,

some conditions in which itis desirable to utilize isfuchv abrasivebodies'.v .The"heatfresistancebf the binder, or the resistanceofsuclbindr'sto water, oil, or cooling fluids fvariositypes used during wetgrinding, havenot been entirely satisfactory. Furthermore, with many ofthe prior art binders,

there lare limitations on control of th e' 'p`roperties ofthe-"bindersto suit'-theni for utilization for these 'purposes monachecbj'eefsfofthe presenti-invention is the prodution' of fbrasiv'e "bodiesofl any desired ,typ'e; utilizing irgend-silicon polymers orderivativesfin the production of such abrasive bodies.

Further objects include theproduction'of such bodies which 'shall havethe 'desired properties including heat resistance; and resistance tocooling fluids utilizediuringdrying operations, making them :canineni'ly' Asuitable' for various grind-J' in'g, abading or polishingoperations;`

'Still-furtler'objects'and advantages will ap-` pear from the morevdetailed description setforth below, 4it being understood that thismore cle- 4itailed description is given by way of illustration andexplanation only, and not by way of limitation,-'since Avarious changestherein may be made by those skilled-in the'a'rt without departing fromthe scopeand spiritA of the present'invention.

In connection with: that more detailed descriptionfthere is shown'i'nthe accompanying drawing-'.1 in w l Figureflra front-plan view of one'form of grinding-wheel'fin Figure 21a section on the line 2-2 of Figurel; andin Figure- ,3, a section through a flexible sheet abrasive bodyproduced in accordance with the' present invention.'

In laccordance 4with the present invention, abrasive bodies are producedfrom any of the abrasive grains available by the utilization of organic'silicon' derivatives employed for the purpose of y bondingsuch abrasivegrains into a solid abrasivcbody of any desired form. or for-bond- 2Ving such abrasive grainsV to paper, textile,l cloth, or other flexiblesheet in the production Lof .the flexible sheet type abrasives;v or theorgano-silt,l con derivatives may be utilized to coat the abrasivegrains which `are then bonded together by.

any of the desirable bonding agents available in the art or moredesirably in accordance with the present invention by organic siliconpolymers.

The organic silicon derivatives which will illustrated below, havemarkedly desirable prop` erties for utilization in the production ofabrasive bodies due to the fact that their properties,

can be controlled as desired to give characteristics of heat resistance,resistance to oils such as the hydrocarbon oils, kerosene, etc.,resistanceto caustic andother chemical action, resistance .to water,etc. Furthermore, the properties of these organic silicon derivativescan be controlled to produce the desired degrees of flexibility. Xtensibility, Veompressibility, etc. to accommodate such materials when usedas binders to flexion ofthe.

base on which the abrasive is carried, as for e'x ample, in the'production of abrasive sheets. The

organic silicon derivatives may zbe adjusted'towithstand the highstresses and strains experi-, enced in grinding operations as withgrinding wheels and to prevent failures during wet grinding operationswith such grinding wheels because of the action of cooling agents suchas kerosene,

oils or other hydrocarbons, etc. Furthermore, the

organic silicon derivatives may be produced in.

any desired form from relatively mobile permanent liquids throughflexible gel forms to hard brittle'resins or hard flexible resinousmaterials. In their liquid form, or in solution, in solvents, they maybe utilized for impregnation or wetting of the grains of abrasivefollowed by bonding ofthe grains either with other types of organicsili- -con derivatives or with other binders ordinarily employed in theproduction of abrasive bodies.`

They may thus be employed in monomeric foim and subsequently convertedinto polymeric con-v dition. These considerations exemplify the readycontrol of the properties of the organic silicon derivatives which lendthem to utilization in the production of abrasive bodies.

Mixtures of organic silicon derivatives may be utilized in control ofthe properties of the desiredV bonding agents. Thus organic siliconderivatives convertible to a resilient state may be employed The solidabrasive bodies produced in accordance with this invention may be madefrom any type of abrasive grain desired, as for example, the varietiesof alumina such as emery, corundum, dense fused alumina, porous whitefused alumina, silicon carbide and other hard carbides, quartz, glass,diamonds, flint, garnet, Carborundum and in general both the naturalabrasives and the artificial abrasive grains. The silicon containingabrasive grains such as Carborundum or other silicon carbides, int,quartz, etc. are particularly useful with the organic silicon binders ofthe present invention. Further the binders of this invention arepeculiarly adapted for utilization in the bonding of diamond grainssince -silicon derivatives may be produced which cure or harden atrelatively low temperatures that preclude any disadvantageous eiIect dueto oxidation of the diamond grains at higher temperatures. But whetherutilized for binders with the relatively soft abrasives such as thesiliceous abrasives, sandstones, quartz, tripoli, pumice an l volcanicdusts, or the relatively hard abrasive; such as corundum, diamond,garnet, silicon carbide, fused alumina, and other such hard abrasivescommonly referred to as grits, the organic silicon derivatives arepeculiarly adapted for utilization in the production of these abrasivebodies.

Any desirable methods for producing the solid bodies from the desiredabrasive grains and chosen organic silicon derivatives may be employed.Thus in the production of grinding wheels or grinding stones, theabrasive grains may be mixed with a liquid organic silicon derivative ora solution of an organic silicon derivative in a desired solvent, theorganic silicon derivative being one which is convertible as by heat orother treatment into a resinous polymeric derivative, and the mix thenmolded to the desired form including any desired metal top plate if thistype of Wheel is to be produced, the molding being done under 'pressurein the cold as by means of a hydraulic press, the mold then stripped andthe green wheel baked in an oven for example, to produce the conversionof the silicon derivative into the resinous binder. Or ii desired, theabrasive grains mixed with the polymerizable silicon derivative may besubjected directly to a hot pressing operation to produce the moldedarticle. Or the abrasive grains may be wet with a non-polymerizableorganic silicon derivative and the mix then incorporated with anydesired binder preferably, however, an organic silicon derivativeconvertible into a resinous polymer, molded and heat treated or hotpressed directly by the methods set forth above.

Where the ultimate binding agent is not an organic silicon derivative,but is shellac, methacrylate or other resin, chloroprene, or otherrubber'whether synthetic or natural, etc., advantage is taken of theproperties of the organic silicon derivatives in producing superiorarticles when so utilized. More desirably, however, the grains 4 siredadhesive layer 3, which adhesive layer may desirably be any satisfactorybinder employed in the art for this purpose but more desirably inaccordance with the present invention is a .ilexible organic siliconpolymer; L

The amount of binder employed will` depend on the characteristics of theultimate molded body desired and may, for example, vary from 25% to 75%of the final molded article although for most purposes, an amount oforganic silicon derivative which will give a final product containingfrom 25 to 40% of organic silicon polymer to 7,5% `to of abrasive grainswill be satisfactory for most purposes. The proportions employed dependon the characteristics of the particular organic silicon derivativeutilized and the vphysical properties desired particularly from thestandpoint-of rigidity and elasticity, etc.

As a specific example of producing a molded grinding wheel, fusedalumina grit was mixed `with alkyl silicon hydroxides containing bothmethyl and butyl silicon hydroxides and molded 5 minutes at 175 C. under5000 pounds per square inch pressure. maybe varied and curing may bevcarried out even at atmospheric pressures, although pressures of severalthousand pounds per square inch are preferred. So too the curingtemperature employed may be varied and temperatures of for example fromC. or higher may be utilized.

In the production of abrasive paper and cloth or flexible abrasivediscs, the desired sheet or backing may be rst coated with the desiredsilicon derivative, abrasive grains distributed upon the liquid coatedweb in any conventional man- ,ner,y and the abrasive coated web thensubjected to heat treatment or any other treatment to convert theorganic silicon derivative into the resinous polymer. If desired, asecond coat of adhesives such as of an organic silicon derivative may beapplied over the abrasive grains. The organic silicon derivativesutilized for this purpose may be liquid silicon derivatives which areconvertible by heat or other treatment into resinous polymers, or theabrasive grains may first be coated with a non-polymerizable organicsilicon derivative and applied to the flexible sheet material which hasbeen treated with the polymerizable organic silicon derivative andsubsequently subjected to treatment to produce the resinous polymer. Anarticle 'which may be produced in this way is illustrated in Figure 3where the flexible sheet or backing 4 carries the abrasive particles 5,adherert to the sheet 4 by the organic silicon polymer yThe followingexample will illustrate the production of exible abrasive sheets. Amixture of ethyl and butyl silicon hydroxides was dissolved in tolueneand applied as a coating to paper, using an amount of coating to giveabout 2.5. pounds of silicon derivative per ream of paper sheets 9 x 11inches. Fused alumina particles were electrostatically projected ontothe adhesive coating and the coating dried sufliciently to set thegrains firmly in position. A second application of the solution of'organic silicon derivative was applied, and the abrasive coated paperdried to remove the solvent and finally heat treated,- frst at C. andthen at 175 C'. to produce a resinous polymer binding the'grains to theflexible sheet.

The organic silicon derivatives of the present invention may be utilizedeither by themselves or The pressures employed resins including phenolaldehyde resins, aniline aldehyde resins, acetone formaldehyde resins,alkyd resins, cumarone resins, vinyl resins, styrene resins, acrylateresins including polymeric esters of acrylic and methacrylic acids,diallyl maleate, allyl esters of polybasic acids, and the like.

tion with the organic silicon derivatives are included hydrocarbonsolvents'such as aliphatic and aromatic compounds, namely, hexane,benzene, toluene, etc.; ethers such as dimethyl, diethyl, diisopropyl,dibutyl ethers or mixed ethers; esters such as ethyl, butyl or amylacetates; alcohols, etc. The alcoholic solvents include both thealiphatic alcohols such as methanol, propanol, butanol, phenols such lasphenol, cycloaromatic or alicyclic alcohols such as cyclohexanol, andthe like; glycol ethers such as ethylene glycol mono-n-butyl ether,ketones such as acetone, methyl isopropyl ketone, etc. Where the statedsolvents are not sufhcient to produce the desired solution, mixtures ofsolvents may be employed.

The following will illustrate various organic silicon derivatives thatmay be utilized in producing the abrasive bodies as set forth above.Thus the organic silicon hydroxides and more particularly the alkylsilicon hydroxides and aryl silicon hydroxides may be used individuallyor in various mixtures as the bonding material. Examples of theproduction of such products will be set forth below. Mixtures of thealkyl silicon hydroxides and particularly silicon hydroxides containingdifferent alkyl groups in the same molecule may be employed since by theutilization of mixed alkyl derivatives it is possible to modify theproperties of a given alkyl silicon oxide resin in a desired directionto enhance its utility for particular purposes. Lower derivatives likethe methyl derivatives produce hard brittle products while higherderivatives such as the butyl derivatives give products of increasedflexibility. Thus mixed methyl-butyl silicon hydroxides may be employedin order to control the properties as desired or cetyl derivatives maybe incorporated with the methyl-derivatives to-bring about an internalplasticization. Thus the control of flexibility or plasticity of anygiven alkyl derivative may be obtained by the presence of a dierentalkyl derivative enhancing the particular property desired. The use ofalkyl derivatives containing'at least three carbon atoms in the alkylgroup is particularly important in thus modifying the desiredcharacteristics of the compounds.

The alkyl silicon hydroxides may be produced either alone or in mixtureby the use of corresponding alkyl magnesium halides reacted with silicontetrachloride, followed by hydrolysis and dehydration. Or the alkylsilicon hydroxides may be prepared separately and then mixed in thedesired proportions before dehydration.

The following example illustrates the production 'of a mixed methylbutyl derivative.

' Example 1.-61.5 parts of methyl iodide was reacted in ether solutionwith 9.72 parts of magnesium. 'I'his solution was added gradually withrapid stirring to 45.3 parts of silicon tetrachloride in ether solution,and thenreiluxed 1 1/2 hours. It was then hydrolyzed by pouring on iceand was washed repeatedly with water to free it from hydrochloric acidand magnesium salts. Most of the ether was evaporated at about 40 to-4:5? C. to give a concentrated material. 45.2

Among solvents that may be utilized in connec- V parts of normal butylbromide wasreacted in ether solution with 7.29 parts of magnesium. 'Thesolution was added'to 51 parts of silicon tetrachloride, and thenreuxed, hydrolyzed, Washed and concentrated to a syrup containing butylsilicon hydroxides. AMixtures of the above methyl and butyl siliconhydroxides vin various proportions were producedand the several mixturesgradually heated to 160`C. and kept at that temperature for 2O hours.The materials high in butyl cured to hard, brittle resins, while thosehigh in methyl were somewhat rubbery.

Example 2.-16.6 parts of normal amyl bromide was mixed with 15.6 partsof methyl iodide and reacted in ether solution with 4.86 parts ofmagnesium. This solution was added slowly withl i acted in ethersolution with 4.86 parts of magnesium. This solution Was added slowlywith stir-v ring to 30.9 parts of silicon tetrachloride in ethersolution. It was then refluxed 2 hours, hydrolyzed, washed andconcentrated as inv Example 3. It was heated gradually to C. and keptthere l5 hours and then heated at 175 C. for 14 hours. The materialcured to a rubbery resin.

The mixed-alkyl combinations thus produced may include different alkylgroups attached to the same silicon atom, or mixtures of diierent alkylsilicon oxide derivatives, or both. These novel silicons have thermalstability greater than the usual coating and bonding agents. They may beapplied by dissolving them in appropriate solvents as set forth aboveand while they are in soluble form, and may then be polymerized in situ.As pointed out, the hard brittle polymers may be plasticized by theaddition of suitable plasticizing agents or by silicon oxide resins oflower softening point.

The relative ratios of the alkyl groups to each other and to the siliconatom in these compounds may vary. In the production of curablecombinations, the average of alkyl groups per silicon atom shoulddesirably be between the limits of 0.5 lto '2.0 alkyl groups per siliconatom and where curing is desired, the particularl proportions selectedparticularly with respect to different alkyl groups in the mixed-alkylsilicon derivatives should be chosen to produce the desired propertiesas set forth herein.

The above examples illustrate the production of mixed-alkyl siliconhydroxides and their utilization in the production of resins and thesematerials either individual alkyl silicon hydroxides or mixed hydroxidesprepared in the manner set forth above may be used as bonding agents inthe production of solid abrasive bodies as set forth above. However, aWide variety of other types of silicon derivatives may be utilized. Thuscopolymerization products may be produced from a silica derivative,reacted with an organic substituted silicon derivative, so thatcopolymerization products are produced in which relatively inexpensivematerials such as esters of orthosilicic acid, or an acyl silicon may beutilized inthe production of stable, coherentresinous products havinghigh heat stability, good color and chemical resistance. Generally thereaction products of this type may be produced from a silica derivavtiveselected from the group consisting of organic orthosilicates, silicontetro-acylates, and silicon halides, with an organic substituted siliconderiva.-

tive selected fromthe group consisting of organic orthoslliconates,organic silicon hydroxldes, organicvsilicon acylates, and organicsilicon halides, the organic groups in such stated compounds desirablybeing selected from aliphatic and carbocyclic radicals. The organicsilicon derivatives may carry substituent groups therefor, suchas alkyl,alphyl, aryl, alkynyl, alkenyl, aralkyl, alkanyl, oleflnyl, non-aromaticcarbocyclic, and the like, and one or more of such groups may be presentin mixed derivatives utilized in producing products in accordance withthese derivatives. 'I'he reactants may be monosilicon derivatives, orpolysilicon derivatives, such as silicon tetrachloride. disiliconhexa-acetate, disilicon hexa-chloride, hexa ethyl disiliconate and thelike. The silica derivatives mayv be esters such as methyl orthosilica,ethyl orthosilicate, butyl orthosilicatel phenyl orthosilicate and thelike, or acylates such as silicon tetraformate, silicon tetroacetate,silicon tetrabutyrate, and the like.

Thus mixtures of alkyl silicon chlorides and silicon tetrachloride maybe hydrolyzed to produce cohydrolytic products which may be dehydratedto a clear resin. Or mixtures such as alkyl alkoxy silicon and ethylorthosilicate may be" hydrolyzed together and subsequently heated togive clear hard resins.

The following examples will illustrate the production of different typesof such derivatives.

Example lL One mole of ethyl orthosilicatc and 2 moles of Water weremixed together and sufficient alcohol added to give a clear solution.The solution was refluxed for 3 hours. A somewhat viscous productcontaining some silica was produced. This was mixed in equal volumeproportions with n-butyl silicon trihydroxide. Such solutions andmixtures may be utilized in producing the solid abrasive bodies inaccordance withy the present invention. The stated derivative of thisexample when heated to 140 C. gives a hard, clear resin.

Example 5.-2 parts of an alkyl silicon hydroxide, made from 0.5 moleethyl bromide, 0.75 mole n-butyl bromide and 1 mole of silicontetrachloride followed by hydrolysis, were mixed with l part of ethylorthosilicate and 3 parts of acetic anhydride. The solution was heatedto boiling. It thickened rapidly and on being cast set to a white gelwhich became a transparent, hard resin on heating up to 130 C. toeliminate acetic anhydridc and ethyl acetate which had formed.

Example 6.-An ether solution of 4 parts of ethyl silicon trichloride wasmixed with l part of silicon tetrachloride. The mixture was hydrolyzedby pouring on cracked ice. There was no evidence of precipitated silica.The ether may be separated and the product used for bonding purposes asset forth herein. At 120 C. heating for several hours, a clear hardresin is obtained. A similar mixture made by mixing 3 parts of ethylsilicon trichlcride with 1 part of silicon tetrachloride was hydrolyzedin the same manner and also on baking gives a clear resin.

The following examples and considerations illustrate the utilization oforganic silicon derivatives in combination with resins such as ureaformaldehyde resins. Urea formaldehyde type resins such as ureaformaldehyde resins per se or resins produced from urea derivatives suchas dicyandiamide, guanidine. alkyl urea or ureas, thiourea or alkylthioureas. biguanide. phenyl l chloride in the presence of magnesium.Another urea and the like, are compatible with the organic siliconderivatives in limited proportions and may be utilized in combinationtherewith for the bonds for the production vof solid abrasive bodies.The organo-siliconols utilized in these combinations may be thoseproduced as set forth above. Or-

gano-silicon acylates having the general formula RzSi(OH)f OR")z, whereR is an organic group as specified above and R" is an acyl group. :n isa positive number less than 4, either an integer or fractional, y-l-z isequal to 4 2 and a is not zero. More particularly, such acylates .mayhave the formula R1Si(OR")4-z, where R, R" and :r have the values setforth immediately above.

The siliconols and acylates have restricted compatibility with urearesins and where clearproducts are desired should not be utilized inamounts of more than 5 to 10% to produce the desired compatibility.However, the organic alkoxy silicons. particularly the alkyl alkoxysilicons, such as the alkyl alkane siliconates including ethyl alkanesiliconate. have excellent compatibility in amounts up to 50% Suchorgano-alkoxy silicons may be represented by the general formulaR1Si(OH)y(OR)z, where R and R are the same or different radicalsselected from .the groups indicatedA above in connection-for thecorrespondlngA substituents in the siliconols, :r is less than 4. y+z isequal to 4 1, and z is not zero, :c being either an integer or fraction.More particularly such alkoxy silicons will have the formula RISHOR')4-1. where R, R' and a: have the values set forth immediately above inthe general formulation of the alkoxy silicons. The following examplesillustrate formulations where urea resins are utilized in combinationwith the `6rganic silicon derivatives.

Example 7.-Three parts of dimethylol urea were mixed with 40 parts ofn-butanol and 0.3 part of an amyl silicon hydroxide obtained from thehydrolysis of the reaction product of one mole of n-amyl bromide and onemole of silicon tetramixture was made using 0.16 part of the above Theseformulations and 5% respectively of the silicon hydroxide. On removal ofwater and excess butanol.,.clear products are obtained which may bebaked at C. for 1 hour, to give hard final polymers. These lacquersolutions may be illustrated as set forth above in the production ofsolid abrasive bodiesemployed either to wet the grains of the abrasivebody or as the bonding agents in the production of flexible types ofabrasive paper, etc.

Example 8.-Three parts of dimethylol urea and 1 part (25% based onnon-volatiles) of ethyl ethane orthosiliconate (C2HsSi(OC2H):|) preparedby the action of ethyl magnesium bromide on ethyl orthosilicate weremixed with 40 parts of n-butanol and `10 parts of ethylene glycolmono-n-butyl ether. One-tenth parts of o`phos lacquer is produced whichmay be utilized as set forth above in the production of solid abrasivebodies. Baked at 140 C. for l hour it produces a' clear hard product.

While organo-siliconols, organo-alkoxy silicons, and organo-siliconacylates are particularlyemphasized above for inclusion in thecompositions forvproducing blends with urea-formaldehyde type resins, itis not intended that theorgano-silicon derivatives must be utilized inexclusion of each other, but mixtures of two or cal; resistance, etc.

more of the various types oforgano-silicon derivatives utilized in lthe'same composition, using two 4or more siliconols, alkoxy silicons. oracylates in the same composition, ormixtures of one typeoftorgano-siliconderivatives,with those of another can be employed. i

Further illustrating the possibility of the utilization of blends of theorgano-silionols with other types of synthetic' resins, the followingillustrates the utilization of melamine aldehyde type resins inconjunction with the siliconols. Thus the organic siliconA derivativesmay be compounded with amino ring compounds selected from the groupAconsistingA of amino triazines, polyamino triazines, amino triazols,polyamino triazols, amino diazines, polyamino diazines,

vamino diazols, polyamino diaz'ols, and mixtures thereof. The amino ringcompounds and particularly the amino triazine aldehyde resins,specifically melamine-formaldehyde resins, are compatible in allproportions with the organo silicon resins andyield products of improvedcharacteristics as'to color retention, heat resistance, chemi- Themelamine type resins may be utilized with alkyl silicon hydroxides,alkyl lsilicon acylates, and alkyl alkoxy silicons. The organic siliconderivatives may generally be represented -by the formula (Rn-Si-(ORlM-I,where .r is 'an integer or fraction less .than four, and where R is analkyl, aryl, alkaryl, alphyl, olefinyl, alkenyl, alkynyl, aralkenyl,cycloaryl, and the like, and R1 may be any of the above stated groups asWell as hydrogen, and also RzCO- where Rz may be any of the above statedgroups as well as hydrogen. These organo-silicon derivatives include forexample, methyl silicon hydroxides, ethyl silicon hydroxides, propylsilicon hydroxides, butyl silicon hydroxides, amyl silicon hydroxides,mixed alkyl silicon hydroxides, methyl methane orthosiliconate, ethylmethane orthosiliconate, ethyl ethane orthosiliconate, ethyl propaneorthosiliconate, ethyl butane orthosiliconates, ethyl pentane ororthosiliconate, ethyl silicon acetates,. methyl silicon acetates, butylsilicon acetates, ethyl silicon propionates, phenyl silicon benzoates,and the like, as well as mixed organic silicons,` such as the alkylsilicon derivatives referred to, and also the organo-silicon derivativesderived from disilicon hexahalides, silicon oxyhalides, polysilicontriazines, or aminotriazoles, polyaminotriazoles, s

aminodiazines, polyaminodiazines, aminodiazoles,

' polyaminodiazoles, and such amine containing ring compounds may beutilized either as individual compounds, or in various mixtures thereof,either between themselves, or in mixture with other compounds, such as aurea compound including urea and its derivatives such as thiourea,biuret, dicyandiamide, guanidine, biguanide and the like.

The compositions may be utilized by blending the desired constituents bymeans of a solvent, the compositions being employed subsequently forbonding agents either retaining the solvent therein, or after removal ofthe solvent following the blending operation. Thus solutions may beproduced and utilized for treatment of the abrasive grains as set forthabove, or in the treatment of flexible sheets to which the abrasives areto be bonded. Or they may be utilized in the preparation .of moldingcompositions to produce molded bodies of the abrasive grains as setforth 'above The following examples will illustrate the production `ofthese combinations with melamine type resins.y

Example 9.-Three parts of n-amyl silicon hydroxide prepared by thehydroylsis of the reaction product obtained from amyl bromide andsilicon tetrachloride in a molecular ratio of 1:'1 reacted in thepresence of magnesium and then hydrolyzed, was mixed with 10 parts of amelamine-formaldehyde solution produced as set forth below. Fifty partsof n-amyl alcohol was added and the mixturel heated. Forty parts ofn-amyl alcohol and some water were taken off through a column in 1 hourof distillation. A clear lacquer solution is produced which may beutilized as set forth above and when baked at 140- C. yields a clear,hard product.

The melamine-formaldehyde resin employed may be producedv as follows. Amelamineformaldehyde resin solution and amyl alcohol was made by mixing63 parts of melamine, 203 parts of 37% formaldehyde solution, 250 partsof n-amyl alcohol and parts of methanol. The`solution was refluxed for 3hours, then the water and methanol distilled off. More vamyl alcohol wasadded and the nal solution made up to 31% solids. l

Example IIL-One part of n-amyl silicon hydroxide produced as set forthin Example 9 above, was mixed with 38 parts of a 50% solution ofvmelamine-urea-formaldehyde resin. The latter solution was made by mixing12.6 parts melamine, 6 parts urea, 57 parts 37% formaldehyde solution(pH=7) `and 100 parts of 1- butanol. The solution was refluxed togetherthen some of the` water distilled off. The solution was renderedslightly acid and the remainder of the water and some butanol weredistilled 01T. Fresh butanol was. added and the solution concentrated to50% solids. The mix*- ture of amyl silicon hydroxide andmelamineurea-formaldehyde resin solution was diluted with 50 parts ofl-butanol and heated under a column. Forty parts of butanol was removedby distillation. A clear lacquer was thus produced which may be utilizedin accordance with the present invention and on baking at C. yields aclear, hard product.

Having thus set forth our invention, we claim:

1. An abrasive article comprising abrasive' grains bonded by a resinouscondensation product of an organic derivative of ortho silicic acid inwhich an average of 1/2 to 2 hydroxyl groups per molecule of orthosilicio acid have been replaced by monovalent hydrocarbon radicals.

2. An abrasive article comprising abrasive grains bonded by a resinouscondensation product of an organic derivative of ortho silicio acid inwhich an average of 1/2 to 11A; hydroxyl groups per molecule of orthosilicic acid have been replaced by phenyl and methyl groups.

3. An abrasive article comprising abrasive grains bonded by a resinouscondensation product of an organic derivative of ortho silicio acid inwhich an average of l/ to 11/2 hydroxyl groups per molecule of orthosilicio acid have been replaced by ethyl groups.

4. An abrasive article comprising abrasive grains bonded by a resinouscondensation product of an organic derivative of ortho silicio acid inwhich an average of about 1 to 2 hydroxyl groups per molecule of orthosilicic acid have been replaced by alkyl and aryl radicals.

5. An abrasive article comprising labrasive 1'1 grains bonded by aresinous condensation product of an organic derivative of ortho silicicacid in which an average of. about 1 to 2 hydroxyl groups per moleculeof ortho silicio acid have been replaced by phenyl and methyl groups.

6. An abrasive article comprising abrasive vgrains bonded by a resinousorgano-silicon oxide 8. An abrasive article comprising `abrasive grainsbonded by a, resinous condensation product of an organic derivative ofortho silicic acid in which an average of about 1 to 2 hydroxyl groupsyper molecule of ortho silicio acid have been replaced by ethyl groups.

9. A solid abrasive body comprising abrasive grains bonded by a resinouscondensation product of an organic silicon derivative having the formulaR1Si(OR')4-1, Vwherein R is a monovalent hydrocarbon group, :c is anaverage of 1/2 to 2, and R' is selected from the group consisting ofhydrogen. monovalent hydrocarbon groups, and acyl radicals.

10. In the method of making abrasive articles',

the steps of bonding a quantity of abrasive. grain with a. resinouscondensation product of an organic silicon derivative having the formulaRSi(OR/)4 wherein R is a. monovalent hydrocarbon group, a: is an averageof 'i1/2 to 2, and RJ is selected from the group consisting of hydrogen,monovalent hydrocarbon groups. and

acyl radicals,'said organic silicon derivative being convertible by heatinto a resilient conversion product. d

JOHN B. RUST.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED -s'rA'rEs PATENTS Number Name Date Y 2,501 vanderburgh Maij;- 5.1867 172,019 Brock Jamil, 1816 224,078 Copeland 'Feb.'3. 1880 942,808Baekeland Dec. 7, 1909 1,775,631 Carlton Sept.,16, 1930 2,058,844 Vaughnoct. 2"?, 1936 2,232,389 Jurkat Ifeb. 18, 1941 2,258,218 Rochow oct.-'1,1941 2,375,998 McGregor et a1.' May 15, 1945 2,438,520 Roble et a1.Mar. 30, 1948 2,481,349 Robie sept. 6, 1949

1. AN ABRASIVE ARTICLE COMPRISING ABRASIVE GRAINS BONDED BY A RESINOUSCONDENSATION PRODUCT OF AN ORGANIC DERIVATIVE OF ORTHO SILICIC ACID INWHICH AN AVERAGE OF 1/2 TO 2 HYDROXYL GROUPS PER MOLECULE OF ORTHOSILICIC ACID HAVE BEEN REPLACED BY MONOVALENT HYDROCARBON RADICALS.